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    <script>
        // 实现一个计数器函数，每次调用该函数返回一个递增的数字
        const createCounter = (a) => {
            let sum = 0
            const counter = () => {
                sum++
                return sum
            }
            return counter
        }


        //实现以下效果
        const counter = createCounter();
        console.log(counter()); // 1
        console.log(counter()); // 2
        console.log(counter()); // 3
    </script>
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